The present invention relates to a detection system and more particularly, a raceway which runs between a pair of panels of a detection system to protect electrical wiring and the like running between the panels.
Detection systems of, for example, the types described in U.S. Pat. Nos. 4,531,117; 4,308,530; 4,135,183; and 3,971,983 generally include an electromagnetic transmitter and receiver for detecting the passage of certain objects, such as tags, markers or metallic items, through the systems. The transmitter usually emits a large signal to which the object responds to result in the production of a low level signal which is detected by the receiver. The system, in order to detect the presence of an object must be able to distinguish between the transmitted and received signals and any unwanted signals. Thus, the above systems are designed so that the transmitter and receiver antennas are nulled to minimize pick-up by the receiving antenna of the transmitted signal. This enhances the detection by the receiver of the much smaller object signal. In addition, it is well known in the art to include a raceway between the panels of such systems to permit travel between the panels over electrical wiring and the like running between the panels.
However, there are several limitations associated with such detection systems utilizing prior raceways. For example, the raceways are generally constructed of a single plate of metal, such as aluminum, which in addition to being heavy, cannot be adjusted in the field to vary the distance between the panels. In addition, prior raceways have been attached directly to the panels which resulted in the load forces associated with travel upon the raceways being transferred to the panels and causing them to wobble or vibrate. Even minute movement of the panels drastically affects the nulled condition between the antennas, and thus interferes with the receipt of the object signal. To compensate, such systems were designed or adjusted to allow for this error by utilizing larger tags or markers. This prevented the systems from attaining optimum sensitivity.
It is conventional to provide protective ramps or bridges, for hoses, cables, wires and the like. For example, bridges for protecting fire hoses are illustrated in U.S. Pat. Nos. 1,956,125; 1,838,746; 594,465; and 72,028. Bridges or cross-overs for electrical wires or cables have also been suggested, as illustrated in U.S. Pat. No. 2,299,356. Further, ramps have also been disclosed for protecting a combination of air hoses and electrical cables, as illustrated in U.S. Pat. No. 4,101,100. However, it has not been suggested that the above structures could be used to isolate the forces associated with travel thereupon to substantially prevent wobbling or vibration of a pair of interconnected panels in close proximity with the structure, and to protect electrical wires and the like running between the panels.
In addition, bridges and ramps have been utilized to accommodate various differences in height between two surfaces to permit movement of wheeled vehicles thereacross, as illustrated in U.S. Pat. Nos. 3,984,891; and 3,423,780. Such structures, like the prior protective devices, are rigid and do not isolate forces associated with travel thereupon to prevent such forces from being transferred to adjacent structures in close proximity.
The prior raceways, as discussed above, do not address the problem of isolating traffic forces from transmission to adjacent panels of a detection system. This isolation of forces is complicated by the fact that electrical wires must pass beneath the raceway and between the panels, and that the panels must be supported in some manner. In addition, despite the need for the system to isolate traffic forces and protect electrical wiring, it must be capable of being assembled in the field and capable of varying with the necessary distance between the panels. Also, it must only be slightly inclined and as flat as possible to minimize interference with travel through the detection system. Further, it must be easy to assemble, disassemble, ship and store. Finally, notwithstanding the above, the raceway must be of sufficient strength and sturdiness to withstand the weight and force associated with travel upon it.